Fix error messages for script-var definitions

crates/eww/src/widgets/widget_definitions.rs

@@ -8,7 +8,7 @@ use gtk::{self, prelude::*, ImageExt};
 use std::{cell::RefCell, collections::HashMap, rc::Rc, time::Duration};
 use yuck::{
     config::validate::ValidationError,
-    error::{AstError, AstResult, ResultExt},
+    error::{AstError, AstResult, AstResultExt},
     parser::from_ast::FromAst,
 };
 

crates/yuck/src/config/script_var_definition.rs

@@ -3,7 +3,7 @@ use std::collections::HashMap;
 use simplexpr::{dynval::DynVal, SimplExpr};
 
 use crate::{
-    error::{AstError, AstResult},
+    error::{AstError, AstResult, AstResultExt},
     parser::{
         ast::Ast,
         ast_iterator::AstIterator,
@@ -66,12 +66,15 @@ impl FromAstElementContent for PollScriptVar {
     }
 
     fn from_tail<I: Iterator<Item = Ast>>(span: Span, mut iter: AstIterator<I>) -> AstResult<Self> {
-        let (name_span, name) = iter.expect_symbol()?;
-        let mut attrs = iter.expect_key_values()?;
-        let interval = attrs.primitive_required::<DynVal, _>("interval")?.as_duration()?;
-        let (script_span, script) = iter.expect_literal()?;
-        iter.expect_done()?;
-        Ok(Self { name_span, name: VarName(name), command: VarSource::Shell(script_span, script.to_string()), interval })
+        let result: AstResult<_> = try {
+            let (name_span, name) = iter.expect_symbol()?;
+            let mut attrs = iter.expect_key_values()?;
+            let interval = attrs.primitive_required::<DynVal, _>("interval")?.as_duration()?;
+            let (script_span, script) = iter.expect_literal()?;
+            iter.expect_done()?;
+            Self { name_span, name: VarName(name), command: VarSource::Shell(script_span, script.to_string()), interval }
+        };
+        result.note(r#"Expected format: `(defpoll name :interval "10s" "echo 'a shell script'")`"#)
     }
 }
 
@@ -88,9 +91,12 @@ impl FromAstElementContent for ListenScriptVar {
     }
 
     fn from_tail<I: Iterator<Item = Ast>>(span: Span, mut iter: AstIterator<I>) -> AstResult<Self> {
+        let result: AstResult<_> = try {
         let (name_span, name) = iter.expect_symbol()?;
         let (command_span, script) = iter.expect_literal()?;
         iter.expect_done()?;
-        Ok(Self { name_span, name: VarName(name), command: script.to_string(), command_span })
+        Self { name_span, name: VarName(name), command: script.to_string(), command_span }
+        };
+        result.note(r#"Expected format: `(deflisten name "tail -f /tmp/example")`"#)
     }
 }

crates/yuck/src/config/snapshots/yuck__config__test__config.snap

@@ -14,7 +14,7 @@ Config(
       widget: WidgetUse(
         name: "foo",
         attrs: Attributes(
-          span: Span(51, 61, 62),
+          span: Span(51, 61, 0),
           attrs: {
             AttrName("arg"): AttrEntry(
               key_span: Span(52, 56, 0),
@@ -52,7 +52,7 @@ Config(
       widget: WidgetUse(
         name: "bar",
         attrs: Attributes(
-          span: Span(467, 478, 479),
+          span: Span(467, 478, 0),
           attrs: {
             AttrName("arg"): AttrEntry(
               key_span: Span(468, 472, 0),
@@ -88,6 +88,7 @@ Config(
       name: VarName("stuff"),
       command: "tail -f stuff",
       command_span: Span(168, 183, 0),
+      name_span: Span(162, 167, 0),
     )),
   },
 )

crates/yuck/src/config/var_definition.rs

@@ -2,14 +2,11 @@ use std::collections::HashMap;
 
 use simplexpr::{dynval::DynVal, SimplExpr};
 
-use crate::{
-    error::AstResult,
-    parser::{
+use crate::{error::{AstResult, AstResultExt}, parser::{
         ast::Ast,
         ast_iterator::AstIterator,
         from_ast::{FromAst, FromAstElementContent},
-    },
-};
+    }};
 use eww_shared_util::{AttrName, Span, VarName};
 
 #[derive(Debug, PartialEq, Eq, Clone, serde::Serialize)]
@@ -25,9 +22,12 @@ impl FromAstElementContent for VarDefinition {
     }
 
     fn from_tail<I: Iterator<Item = Ast>>(span: Span, mut iter: AstIterator<I>) -> AstResult<Self> {
-        let (_, name) = iter.expect_symbol()?;
-        let (_, initial_value) = iter.expect_literal()?;
-        iter.expect_done()?;
-        Ok(Self { name: VarName(name), initial_value, span })
+        let result: AstResult<_> = try {
+            let (_, name) = iter.expect_symbol()?;
+            let (_, initial_value) = iter.expect_literal()?;
+            iter.expect_done()?;
+            Self { name: VarName(name), initial_value, span }
+        };
+        result.note(r#"Expected format: `(defvar name "initial-value")`"#)
     }
 }

crates/yuck/src/error.rs

@@ -122,12 +122,17 @@ impl<T> OptionAstErrorExt<T> for Option<T> {
     }
 }
 
-pub trait ResultExt<T> {
+pub trait AstResultExt<T> {
     fn context_label(self, label_span: Span, context: &str) -> AstResult<T>;
+    fn note(self, note: &str) -> AstResult<T>;
 }
 
-impl<T> ResultExt<T> for AstResult<T> {
+impl<T> AstResultExt<T> for AstResult<T> {
     fn context_label(self, label_span: Span, context: &str) -> AstResult<T> {
         self.map_err(|e| AstError::ErrorContext { label_span, context: context.to_string(), main_err: Box::new(e) })
     }
+
+    fn note(self, note: &str) -> AstResult<T> {
+        self.map_err(|e| e.note(note))
+    }
 }

crates/yuck/src/parser/ast_iterator.rs

@@ -98,7 +98,7 @@ impl<I: Iterator<Item = Ast>> Iterator for AstIterator<I> {
 /// Parse consecutive `:keyword value` pairs from an expression iterator into an [Attributes].
 fn parse_key_values(iter: &mut AstIterator<impl Iterator<Item = Ast>>) -> AstResult<Attributes> {
     let mut data = HashMap::new();
-    let mut attrs_span = Span(iter.remaining_span.0, iter.remaining_span.0, iter.remaining_span.1);
+    let mut attrs_span = iter.remaining_span.point_span();
     loop {
         match iter.next() {
             Some(Ast::Keyword(key_span, kw)) => match iter.next() {